SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8331239797af1f0890713c15dda9c056c9c050610fef9529074efe786f70a3e1' 
  AND token = '86Uk9/5REhKA0EbfGzsubxsIGLmjMyVzWUlAn3kSgRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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