SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21b3a9321618a4663946ddaa2d9ccb35546eaba89e223cb1b564a4975ebe2229' 
  AND token = 'P6vvzeJROqekkc//R+7hP9TeA+xweFnbvQlgykKqzOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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