SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9afabcf3aeb30869006b9cddaa6e53ed127992f197679b80284027119961662' 
  AND token = 'OQHRSobkmKP8LB9XYfTUWvjDfkzVKODNFL1M5DXHMgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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