SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7420dad28e344778a8b1be9415da32efcf9f28074f822ec2ef28ccb63421b15' 
  AND token = 'VTTnioKynxS+NmcGafE9/PJ/jQuKXaju7HdVBBHK/n8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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