SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73f9c09915816beb4845720588a91e7cf1232fdcc25381ebbed766c854ce7c39' 
  AND token = 'ULV+X985IjD4DJMTQPWBs6PA1ZiwPvVzD0n/O997O88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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