SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e778463379b39012614f263a5c9f52b9f7a1e2648ada24f727608510b871bcce' 
  AND token = 'u6HnbhqdMAHvNezIUljlY2T53luhdfGiCVKyUl0smN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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