SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd255f3fb3d6a26e6e7ae19f526966c2d7f60df7d78b4d8f687b4ed25d76c964' 
  AND token = 'EtiAOWkzIvNud0elApJGyzMsnYFHqotyxNsui51cJTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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