SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae6750b8ad698a612bab95fd8eb9b72422def751326a1a8f5d09ea46658e3658' 
  AND token = 'PONr6Yw0t77BnHZEwTcE0lKBTIMXjLn+a2PMbcSNo1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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