SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe174243b4b7b06e7f541e104d8677cc57a365aec1459ea1ee78fe736b40ec5e' 
  AND token = 'DVfO+Kuo6p/aIQufPMjUkCTqdaJVVDLavZB/umyQ4co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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