SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36fdcfb85e0ff9012f6547c7a8ae60cd5092b70af211de4999cfd8bb2ab43848' 
  AND token = 'eJnAAcUg5e7roNqOgx+0qsvQtyMfvD6kXKtsCfz/NOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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