SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa7a575b2e5103faac290f63b0748a3d7eabda2ee9595fbc8e4761c896e69859' 
  AND token = 'saqiw1k+PHmqiRYCKNC4SyWJxHi+6BIQdHV1mb50vrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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