SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '42bc3fe1c090dd21ed03b0cd1d1adfea3a555e1cd8b8b7f5bf475fd79e95e774' 
  AND token = 'RRmihOUOdM5xmRjOWJNvAJRwZ5j7+DqMt1ALE9q0jRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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