SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adecc1cf24f9d1f3f850cee69e702437991bb460235db3ca91b880399adb83fd' 
  AND token = 'slsL3efy6jrHMOvqT7a83vF9fcwjB34044/Z2y29UC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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