SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b382a81b30432ffd75e9708afa1caa8fe88133cb800ffa36585b8d2874057a8f' 
  AND token = 'chxMBsXtiXsjHgMzmJKbtzaxVy6YBh7zJpZZoofx6Bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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