SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6fddbf9159c3b0b765fdb305ec2a50bca9f6c183d092389db7b7824c28145be' 
  AND token = '3ivoOGtQymPJUNqqsQc55aRMOm7FzEttKErYpqXupLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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