SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3817ec32462cc657e0eb947ffd2ae120825fb749af90337dfceea13ec726a3f1' 
  AND token = 'ag1DVAvDoCpCb+YlesyDcI5KHuTX0snB/RLzV/wbQZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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