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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18bcc88e3581970606d517c67dd4d60eb32eebed90a50f5e4205eb7054b4e26c' 
  AND token = 'b3IWlBg7W8cQxk8pSGYNDF2JBI0GjbUL2RD7fX6R8Sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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