SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83b149fe244de6115f43f434395d3e1fa9661d2e26078059bd81e06d89959305' 
  AND token = 'LJfkxhRgq4k5jhxyXrrwuI1DIAdQLUWY8jVWCzIqfd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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