SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398f7e9ccc7c5a32c0e61f57c17031d4e1454dc4c4905370283311be21b00e0d' 
  AND token = 'NlCRJAUq7QjFf1YDbyaUkYUcNyYKfWZCGFGMXrQrIa0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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