SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16f8ac848591338aaefd846362c8a7be6482c280a3cdbabc636e4d2a28806367' 
  AND token = 'gnerGvbhV7ydZCUY2r1TaJ6YwyDDDO/OEbRbwFMbIvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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