SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f95dcb28b50ce2b552de15198e067443c639e920b6227ca1d2952b06b608f9ec' 
  AND token = 'MY3FBnMRZwRvRxzz+iSwUOXL9x2rk9tsY4JsvISu/N8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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