SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '873cad2f5a8ce3733d432562446d235c951ddb464647513971645ff389ae6ee6' 
  AND token = 'UOJ4XJFCgkaEYvtYw8s319RX+kLenAwbq6YlauNTpNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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