SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '266404b600cccddf40c6fdf57b22c30514d8b05cb8732754a9a11634738672d0' 
  AND token = 'GxSus5NvjccHDT4jm4dk3KG47GXe7EqjhNPnqFMaBeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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