SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '551c238fd0c7887798b19fe85da8c099541c582d4a881d0cfb09002d6d1bb432' 
  AND token = '2WvxmRScOk0PdW4pGIFeKltymOvUhbO6uATYRSAJWvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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