SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b68f5df18ab6ffe78a37ca763706bb78088d377cb79c46fd231dfdb9ba034834' 
  AND token = '1eu8YpPWbpW8lr8FLcTE31yjpVaWOGPr/ls/0GijYEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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