SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bcb67e78376b58688251b3eab852499b90b764c754ae30f0a1f383fba3f4315' 
  AND token = '4vPYbYHfxhcduHKpU0JddHEowZTcSjeLv2USYuRwDOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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