SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '577c51643f43e04b90d7639456232040b435daa8a199a481ba9286596adfe53f' 
  AND token = 'iCPpYyURj+bVrdOkAulgfIXdT4M/lVFU0ry+HxKgNZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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