SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a949079346c667c65d72ae0db492218a8738f763f3f04e3d5c020c83eb4a5244' 
  AND token = 'wU1UL0NnMltFvzsqpzIEPGN8n5ezVtA1JTpnIsZljt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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