SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac8a2fb392391cab45f3ddcb02b5baf6275c0e3c9d138f997b6441ece0f6d03f' 
  AND token = 'tBmHxPWZ+1F6WVkvXT2kHuTPP5jizz5pFSq3wg6slfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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