SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd879e58223ec8ff9112d83b4a0316c5af9c35e3e35a7e1750b8638ff42e1932c' 
  AND token = 'U+vpu6bZiSgICH/YvjIRUGlvPfGbfkA50BCrGk5hGio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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