SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81f3780ed578825a2d53d3c1ce8e38de6ba11de7c4d8cabf8111433bc3755cb6' 
  AND token = 'gynkcAoBFFpW6OXPQS1gG70qeCc8CfV6j59ELK4FGBg=' 
  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"
    }
  }
}