SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ad2d8ea7d2c58cde16996707fd758c93432037e23eba3b6cfaa972b0324eef7' 
  AND token = '4MqChgA0cGnDZZPYkIgsAvPEp9yAy+n+EBdhPUkw4VQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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