SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87008fac925e4d7b0185f6cbc6b40f122cf55d58dd360175275649188345992' 
  AND token = 'sTjbeP3rCMmygDbVKBv00OithrdZTGg2gWdw0PY2Xsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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