SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b4f550c864cc28ff984f75b76ca0912ce7fd88d65adff9d835d53b0a00ab727' 
  AND token = '3WdUk7Bx7s2dgRV/vv5df+flXqtqey8zVG/LNpzV+hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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