SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a016198757efaa6a27551ad6c21bc37a8f997b050d0addfce7676a93f27451f2' 
  AND token = 'Ct7ThXRGxVBLvCMWp9p/GFregR/Si4XZMmCenKB6pJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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