SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66614990f0854a491d036b63ef4dd2111399a7d822dcf2b23a0250d2b416a7ce' 
  AND token = 'Klk5bwnqO2r6ThxBXpOTIhB0t6+RizZHdPUeDsV2hUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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