SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e7633ab29191168b4cd2e9b84615a95e688ca426868f3988770a70f2b15156a' 
  AND token = '7K7eZfJX8jatr4fEu22DUntWJgmIFhdR5qCD0GKKBXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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