SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efc1c89e14b623fa94ff762f3241a091a0e7796338909ebea5619a943707ce72' 
  AND token = 'eTClwyj4aZ0BlKF6ZTbZrRxqzBwCzLhsgcf0KbfoThI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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