SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f5971c31950bedcd87087461e38363798d151029b4a66c0793ff7c04499d849' 
  AND token = 'sJvneVYB/vT61FZ0lTaRQerkYZakODHtVgbwnruf5ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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