SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd1ca6283ef394e377063a6eb319474ee510ea7923b08df9752c64a6b8be9db25' 
  AND token = 'K251R7x35Jb4QlBzvgz4WzFAzI3EnfkGpvk/2LUCGXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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