SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02f281c8b76e5c3c8504be8c49a5a2776f9a7f3349f5a62da72120f5b0840f13' 
  AND token = '5jkt59itNuU6xD0QysqW/6S0SPQ+baMsIhm26jrCPj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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