SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd40e8b25e8343fa0c594f60fd4cf119d8b4aa277744294294ebbf5fde93bf11c' 
  AND token = 'vVFQKXrWHWhhLyuIBTiU+bbLCShrPyPIkVf21Frw/VY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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