SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '555e0d0ea054cc2c124b839ee8121bb983e9df73f144544939bf2fcd411c15cc' 
  AND token = 'FLDmqJQJLg960XaVZ/YcUyIZjINZcu5v1Rtd5YGEWtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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