SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b51853a5a72c07d24da6e59e5557299464ecc6182ae2fb2a24f38c7c0cc70b6' 
  AND token = '2qH2O3QYESJnvWIJPmgQrrfAYPpBD3ioY3VqYzyV7Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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