SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1d871426c01f3908e7432d2d961e88f30b81684c68378825367326acc16ce44' 
  AND token = '3sWwpcXWT+9iQAG1A6pr4/uymuvzGYznvQg8D/8tRCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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