SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15192a9eee15d2f9b8834708deef196febe22f2a48a18fabca77b34c945e3851' 
  AND token = '+rvlm7xofmzUDp4PtLOgkyMgga/poGYJ+HvWQjqZwbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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