SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1aacc0c22b5b046f352476e8624d42fdf89441e57fd991a8a0e5ec6d7f32d0b5' 
  AND token = 'KmnnoRi8UGRDuolQBlsXVyqS+zHvEzGvm/mfU7kpE9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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