SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f15330231311269c8f3052a0a997526c41fd5ecf7f45c2a268f29d48877e481' 
  AND token = 'xJafjiPYl6jySo5jR2pjQFg77KZUdqq1nNDvzPp/rfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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