SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47759a732844373fd3ab19add63952da91212fd06cdda3e1b3a2643ca1f21f1a' 
  AND token = 'WliEY8HoYSHl8WYSCNHCal6OZw6rZ+uakLFXNvAWM/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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