SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bcc63b3d000cb6818c708e9297c3bce7635649d718828b065a6547f1c611643' 
  AND token = 'gueqPdOYMrNZq2q9ovZdgt6AnjDOa3MTLbx8PBU4SwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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