SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a74254ea50535e494e4caaeb8749bc03abc4879c0da53e44cd083146dd2e7246' 
  AND token = 'c0jXVnoUxqs10MNVkh+H9dAUInI3/5Niijsk5gKigJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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