SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '49978d104981b13fc196effe171327387e0322dcef99ff2c9efb74026eadc4b6' 
  AND token = 'ZVFhbCkzGHbMRI1HgzAZKm7qnGL8TNg9XTi9DxjTV7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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