SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '327d689cbca959e836d390a0a3ea149fc4bb385750037a6795cd51fb692f4ab7' 
  AND token = 'xdKQwEdBySuxW0jfH3ZyFCnEx7DE25yttMKK449ZA1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}