SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e56e19b88ffaf7928921280cdbde1527ce3d5c838cc87000f112f2a66728923f' 
  AND token = '4/fqU6xgR7xWfAqgpe74Dtzg/VPq3aVxPzIx1yvIf8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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