SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5ec661c6aaf249d3fb6bd6beef2cd4bcb505b15260d319414432c73128dc307' 
  AND token = 'E0eNvZlcZZsjP+SpvPIHvUmRjEA8oobZWfhmucgFWws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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