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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '639376b1cc5112d0e308550afbab6463032c4b0c00721568e65524f325e1ca6c' 
  AND token = 'doqO9ln5dJHPTFL9ypFBYRuAW+sq4CSvAtugg46Szyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}