SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9cf4c171f91cc7eb21dc5c3b75939f5b3ee03fb33aace9b212600eeb0dc68dc' 
  AND token = 'suDCtkNTEvjUWIGwZRb+louMaDIoohwjLdfwhZrF7wY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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