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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1255eed443fdc3231e149884c066840ceaf09a1da7190cb1be7b223883873895' 
  AND token = 'rjlFQpLEbL1PDiJ6ribr9M+CjsxXB8aLXlMf/B1BPPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}