SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86bb7bf8911cba4fa99076a688f6d422e50dcc946ac676715dba5dd49853b505' 
  AND token = 'nDsew7UTTqX9LFWTRGHEP38SiffjXmtBiKUkeHHtNNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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