SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf648697a1a0b22ff5af633a781ddd860aaad977504d20ee7a23b84f8102fe7' 
  AND token = '8BduWxrwVrbtrZ+Pc4uDkTo49Xt0hDZEKpLGzgFsHO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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