SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9394174fc48be0a86f0af9d42c7820c6009f573c9f52593a2ef675ed37b39f4c' 
  AND token = 'tVmQt431gTo8+MQgJ+nhFKlcYGNUf1B/CUIVdzRlELg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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