SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd03223067ef10a1a271567a57ef6cf688afd51b021a1b83147da2a0ede8abf1' 
  AND token = 'sXLNoutQhNZfxg8Z2WxJ+umQeNn7YnAfONnSbebH8fQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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