SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eb21881c89d673546c2fded1d9897924464aa9527c5fe17b3fcc8df2fce5431' 
  AND token = 'QOHwNxuLx/yGRjSpCdJT7tE0ZDX8yCjvuDp/CfdNptM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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