SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2dc6510d7ffe112b54c541dc14972c762a41ee258b012268a24c8936ee9353a' 
  AND token = '8A14ODJ6TjjF3eOy3GZffzNawF2ryQJ8mJCnpR1X5Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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