SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6c273308168da559f835dd879c1b7fb2b1f2751e61475b7e81bb02facd71075' 
  AND token = 'ZazGMlyVnBQnYMDLklrvsoZjjmYx0HFz5Ynb7b6J+uQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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