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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f846b7168ad988b1c7f69a8120eae21aafaffa505710e23bdf4a23aa691cc7' 
  AND token = 'erjDbSn4VmNZQFg97tjz+q9ljJm5hGv5+cieqTxeFQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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