SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '70f49304f3d21993a4467533d643d7aca73c43f6b749cf68782ba45947a3f717' 
  AND token = 'vDMsVftcS1x5LAKDz1HOmzLGEmqgujIEYkb0VYvusRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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