SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '769523b7109157654b23b5648f1fe478214901d71510b91d186e15a15777e661' 
  AND token = 'fvLnsac1Cwx5AHA+zXD75gEU6j5WNw8gJpyADBiezY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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